A semiconductor device, an organic EL device, or the like is manufactured by performing a processing such as, for example, etching, chemical vapor deposition (CVD), or sputtering, on a substrate to be processed. Conventionally, as a plasma processing apparatus that performs a predetermined plasma processing on a processing target object such as, for example, a semiconductor wafer, a plasma processing apparatus using a radial line slot antenna has been known. The radial line slot antenna is provided above a dielectric window that is provided in a ceiling opening of a processing container in a state in which a slow wave plate is provided on a slot plate having a plurality of slots, and the center of the radial line slot antenna is connected with a coaxial waveguide. With this configuration, microwaves generated by a microwave generator are radially transmitted by the slow wave plate in the diametrical direction via the coaxial waveguide, generate circularly polarized waves by the slot plate, and then, are radiated from the slot plate to the inside of the processing container through the dielectric window. Then, high density plasma having a low electron temperature may be generated by the microwaves under a low pressure in the processing container. A plasma processing such as, for example, a film forming processing or an etching processing, is performed using the generated plasma.
In such a plasma processing, it is required to perform a stable plasma processing in order to improve a yield. However, a phenomenon that plasma ignition is failed or delayed may happen. When the ignition is delayed, the plasma processing is not normally performed, resulting in a decrease of the yield.
As a means for improving plasma ignitability, a preset function may be exemplified that presets a specific position of a needle (probe) of a tuner that performs a power control. While a method for implementing the preset function has been conventionally proposed in impedance matching by a variable matcher, no simple method for deciding an optimal preset position in impedance matching by a tuner exists in the present circumstances. Thus, conventionally, all the available settings are implemented to find out and decide an optimal preset position from the settings, which requires a significant time to decide a preset position.
For example, Japanese Patent Laid-Open Publication No. 06-188221 discloses a microwave auto-tuner that directly detects an emission intensity of plasma and tunes microwaves such that the detection value becomes maximum. Japanese Patent Laid-Open Publication No. 05-094955 discloses a plasma processing apparatus, in which a tuner and a microwave generator are controlled such that in-plane density distribution of microwave discharge plasma may be uniformized.